1. Field of Invention
This invention relates to foil type devices as well as vortex generators and vortex attenuators, specifically to such devices which create pressure differentials through a fluid medium.
2. Description of Prior Art
Numerous prior art attempts to reduce induced drag include the use of winglets to block undesirable cross flow conditions and the formation of tip vortices. Even the best winglets only reduce the tip vortex by about 20% maximum, and therefore 80% or more of the problem still exists. In addition, prior winglets add significant weight, additional surface drag, profile drag, parasitic drag and induced drag from vortices formed at the tips of the winglets, and these factors often reduce the net benefits to around 2% to 3% improvements. These devices typically work at only one flight speed and angle of attack.
U.S. Pat. No. 5,634,613 to McCarthy (1997) uses an anhedral tip droop which is mounted at a divergent angle of attack to produces a counter vortex. Methods are not disclosed for maximizing net benefits by minimizing downward lift, profile drag, and flow separation.